JPWO2016088560A1 - Method for producing filter molded body - Google Patents

Abstract

A filter molded body using graphene having water passage holes of a desired size is manufactured by an easy process. A method for producing a filter molded body having a layer of graphene 2 as a filtering material, the step of forming a layer of the support 5 on the surface of the graphite 1, and the formation of support water passage holes in the layer of the support 5 A step of peeling the support layer 5 from the graphite 1 in a state where the graphene 2 layer on the surface of the graphite 1 is adhered to the layer of the support 5; And a step of forming a graphene water passage hole by heating at a low temperature for a predetermined time in air containing oxygen at 250 ° C.

Description

  The present invention relates to a method for producing a filter molded body, and particularly to a method for producing a filter molded body having a filter using graphene.

  In recent years, filter molded bodies employing graphene with fine water passage holes have been used as filters for removing fine particles such as ions from water, other solutions, or gases (patents) Reference 1).

In general, graphene is formed on the surface of a copper foil or the like by a chemical vapor deposition (CVD) method (Patent Document 2). Therefore, conventionally, transfer is called transfer to a desired support when using graphene as a filter molded body. A process was required (Patent Document 3).
In the transfer step, a PMMA is spin-coated on the exposed surface of the graphene formed on the copper foil to form a thin protective film and dried, and then the Cu etching solution heated to 50 ° C. with the copper foil down Remove the copper foil.
Next, the thin film of PMMA and graphene is washed with ultrapure water and scooped up on a silicon substrate having a hydrophilic surface.
Thereafter, the thin film is rolled up with a desired support made of resin or the like and dried, and acetone protection and IPA immersion are alternately repeated several times to remove the protective film of PMMA.
Finally, the graphene could be transferred to the support by drying the support and the graphene.

In such a conventional transfer process, chemicals and the like are consumed and labor is required, and productivity is low.
In addition, extremely thin graphene may be damaged in the process of forming or removing the coating on the surface of the graphene layer, or scooping up or separating it with a silicon substrate or the like.

In addition, conventionally, in order to form a water passage hole in graphene, there is a method of heating in high-temperature air of about 300 to 500 ° C. or in a mixed gas of oxygen and inert gas (nitrogen, argon, helium, etc.). (Patent Document 1).
However, this method not only damages the film resist supporting graphene due to heat, but also makes the holes difficult to control due to the combustion reaction of graphite, and the size of the water holes that open to graphene is not uniform. Therefore, it was unsuitable for use in a filter molded body requiring uniform water passage holes.
In addition, the burning residue of the support such as resin generated during combustion contaminates the graphene and may deteriorate the performance of the filter molded body.

In addition to graphene, there are also ion selective filters using carbon nanotubes (Patent Document 4) and carbon nanohorns (Patent Document 5) (hereinafter, single-walled carbon nanohorns are abbreviated as SWNH).
As another method for forming a water passage hole in the carbon nanomaterial, there is a method in which nitrate is attached to the carbon nanomaterial as an oxygen supply means and heated in a vacuum of 300 ° C. or in an inert gas to form the hole. (Patent Document 6).

Special table 2013-536077 gazette JP 2013-144621 A JP 2013-107789 A Special table 2011-526834 gazette International Publication Number WO2003 / 099717 (Republished Patent) JP 2009-073727 A

  This invention is made | formed in order to solve the said problem, and makes it a subject to manufacture the filter molded object using the graphene which has a water flow hole of a desired magnitude | size by an easy process.

In the present invention, means for solving the above problems are as follows.
1st invention is the manufacturing method of the filter molded object which has a layer of graphene as a filter medium, Comprising: The process of forming the layer of a support body on the surface of a graphite, and a support body water passage hole in the layer of the said support body A step of peeling off the support layer from the graphite in a state where the graphene layer on the surface of the graphite is attached to the support layer, and an oxygen layer at 160 to 250 ° C. And a step of forming a graphene water passage hole by heating at a low temperature for a predetermined time in air containing water.
In the present invention, the order of each step is not limited to the order of description of each step. Therefore, the support water passage holes may be formed in the support layer after the support layer and the graphene layer are separated from the graphite. Alternatively, a support water passage hole may be formed in the support layer in advance, and then the support may be attached to the graphite to form a support layer on the surface of the graphite.

  In a second aspect of the invention, the support is a negative photoresist, and the support water passage hole of the photoresist should be formed in the step of forming the support water passage hole in the layer of the support. And a step of exposing a portion other than the portion.

  The third invention is characterized in that the step of heating and holding the graphene layer at a low temperature to form the graphene water passage hole is performed in an air containing oxygen at 200 to 250 ° C.

A fourth invention is a method for producing a filter molded body having a graphene layer as a filter material, the step of forming a graphene water hole in the graphene layer on the surface of the graphite, and the graphene layer in the graphite A step of forming a support layer on the existing surface; a step of forming a support water passage hole in the support layer; and the support in a state where the graphene layer is attached to the support layer. And a step of peeling the layer from the graphite.
In the present invention, the step of forming the support water passage hole in the support layer may be reversed with respect to the other steps. Therefore, the support water passage holes may be formed in the support layer after the support layer and the graphene layer are separated from the graphite. Alternatively, a support water passage hole may be formed in the support layer in advance, and then the support may be attached to the graphite to form a support layer on the surface of the graphite.

According to the first invention, a support layer is formed on the surface of the graphite, and the support is peeled from the graphite in a state where the graphene layer on the surface of the graphite is adhered to the support layer. Thus, it is possible to easily form a graphene layer on the support without requiring a transfer process or the like.
Further, the graphene layer is heated and maintained at a low temperature for a predetermined time in air containing oxygen at 160 to 250 ° C. to form a graphene water passage hole, whereby the reaction is gentle and easy to control, and the heating time is short and long. By control, holes of a desired size can be formed uniformly in graphene. In addition, since the support can be prevented from being damaged by heating the graphene at a low temperature, the graphene can be prevented from being damaged.

According to the second invention, the support is a negative photoresist, and the support water passage hole of the photoresist is formed in the step of forming the support water passage hole in the layer of the support. By including a step of exposing a portion other than the portion to be performed, a filter molded body can be formed without passing through a transfer step that causes damage to graphene.
Moreover, the size and shape of the support water passage hole formed in the resist can be controlled in detail by using a photolithography technique that does not expose only the portion where the support water passage hole is to be formed. Thus, it is possible to form a support water passage hole in the film resist having a small influence on the ability of graphene as a filter while increasing the strength as a support.

  According to the third invention, the step of heating and holding the graphene layer at a low temperature to form the graphene water passage hole is performed in air containing oxygen at 200 to 250 ° C., so that it can be performed in a relatively short time. It is possible to reliably form graphene water holes in graphene.

According to a fourth aspect of the present invention, the support layer is formed on the surface of the graphite where the graphene layer is present, and the support layer is attached to the support layer. By exfoliating from the graphite, a graphene layer can be easily formed on the support without requiring a transfer step or the like.
In addition, a graphene water hole is formed in the graphene layer on the surface of the graphite and then attached to the support, and the support layer is formed from the graphite in a state where the graphene layer is attached to the support layer. By peeling, a filter molded body having graphene water passage holes can be easily formed.

It is a figure which shows the manufacturing method (process) of the filter molded object which concerns on 1st embodiment of this invention, (a) is a top view, (b) is sectional drawing. Also, (1) is at the start, (2) is at the time of attaching the graphite and the film resist, (3) is at the exposure of the film resist, (4) is at the development of the film resist, (5) is at the film resist and At the time of exfoliation of graphene from graphite, (6) shows the time of perforation of graphene. It is a figure which shows the manufacturing method (process) of the filter molded object which concerns on 2nd embodiment of this invention, (a) is a top view, (b) is sectional drawing. Also, (1) is the start, (2) is the spin coating of the liquid resist, (3) is the exposure of the resist layer, (4) is the development of the resist layer, (5) is the graphite of the resist layer and graphene At the time of peeling from (6), (6) shows the time of perforating graphene. It is a figure which shows the manufacturing method (process) of the filter molded object which concerns on 3rd embodiment of this invention, (a) is a top view, (b) is sectional drawing. (1) is when the graphite is perforated, (2) and (3) are when the graphite and the film resist are attached, (4) is when the resist layer is exposed, (5) is when the resist layer is developed, (6) shows the film resist and graphene being peeled from the graphite. It is a graph which shows the test result which measured the nitrogen adsorption amount of SWNH of a graphene structure, (a) is what used SWNH processed at 250 degreeC, (b) is what used SWNH processed at 200 degreeC. is there. It is a graph which shows the test result which measured the nitrogen adsorption amount of SWNH processed at 180 degreeC. It is a graph which shows the test result which measured the quantity of each ion which permeate | transmits the hole formed in SWNH, (a) uses SWNH processed at 250 degreeC, (b) uses SWNH processed at 200 degreeC. It was. It is a graph which compares and shows the test result which measured the quantity of each ion which permeate | transmits the hole formed in SWNH for every temperature which heated SWNH. It is explanatory drawing which shows the usage method of the filter molded object which concerns on embodiment of this invention. It is a graph which compares and shows the test result which measured the quantity of each ion which permeate | transmits the hole formed in the graphene for every temperature which heated the graphene.

Hereinafter, the manufacturing method of the filter molded object which concerns on 1st embodiment of this invention is demonstrated.
In this filter molded body, graphene is used as a filter.
In the present invention, a support layer is formed on the surface of the graphite 1, and the support is peeled off from the graphite 1 in a state where the graphene layer on the surface of the graphite 1 is attached to the support layer. A graphene layer is formed on the surface.

As the graphite 1, it is preferable to prepare graphite having good crystallinity.
For example, HOPG (highly oriented pyrolytic graphite) and quiche graphite can be used.
In this embodiment, 1 cm ² , 1 mm thick HOPG is prepared, Scotch tape (registered trademark) (manufactured by 3M) is attached and peeled off, and the basal surface is peeled off to prepare the clean surface to be exposed. Keep it.

As shown in FIG. 1 (1), a film resist 3 made of a photoresist was used as a support for holding graphene in a filter molded body.
The performance required for the photoresist used here is strong enough to be used as a support, is a negative photoresist whose solubility in a developing solution is reduced by exposure, and polyimide or epoxy resin This is a resin having high heat resistance.
In this embodiment, a film resist “Raytec” manufactured by Hitachi Chemical Co., Ltd., which is used as an insulating film of a printed circuit board as a solder resist made of epoxy resin, is used.
Laytec is a film resist having a three-layer structure of a protective layer 4, a resist layer 5, and a support layer 6. The resist layer 5 is a layer made of a solder resist made of epoxy resin. The support layer 6 is formed on one surface of the resist layer 5 and protects the resist layer 5. The protective layer 4 is attached to the opposite surface of the resist layer 5 and serves to protect the resist layer 5 until it is attached to the graphite 1. The protective layer 4 and the support layer 6 can each be picked and removed from the resist layer 5 by hand.
Since a thick film resist 3 is easier to use as a filter, it is preferable to use a film resist as thick as possible. In this embodiment, a RAYTEC (model number FZ-2730GA) having a film thickness of 30 μm is used.

As shown in FIG. 1 (2), in order to form a filter molded body, first, a film resist 3 is attached to the clean surface of the basal surface of graphite 1.
A vacuum laminator is used for pasting in order to remove the air between the film resist 3 and the graphite 1 and firmly press the air. For example, a laminator for semiconductor processes such as MVLP-600 manufactured by Meiki Seisakusho Co., Ltd. is optimal, but a home laminator or a simple laminator may be used.
The protective layer 4 of the film resist 3 is peeled off by hand, placed so that the resist layer 5 is in close contact with the clean surface of the graphite 1, placed in a laminator film, and vacuum-pressed with a vacuum laminator at −50 kPa for 20 seconds.
This step is performed in the yellow room in order to prevent the film resist 3 from being exposed.

Next, the graphite 1 and the film resist 3 are taken out of the laminator film, pressurized at 0.4 MPa while being heated on a hot plate heated to 80 ° C. for 40 seconds, and then naturally cooled to room temperature. In this step, the resist layer 5 adheres to the graphite 1.
Then, it leaves still at 25 degreeC for 15 minutes. Here, by allowing the film resist 3 (resist layer 5) to settle, exposure described later can be performed uniformly.
These steps are also performed in the yellow room in order to prevent the film resist 3 from being exposed.

Next, as shown in FIG. 1C, the film resist 3 is exposed to stabilize the resist layer 5 of the film resist 3 so that it does not dissolve in the solvent.
In the exposure process, 180 mJ / cm ^{2 is} irradiated by an i-line stepper using a high-pressure mercury lamp. For example, EXP-2031 manufactured by Oak Manufacturing Co., Ltd. can be used.
Further, at this time, a part of the surface of the film resist 3 is masked with chrome so that the portion covered with the mask is not exposed and is removed by development described later. Can be formed.
For example, circular chromium having a diameter of 500 μm is arranged vertically and horizontally so that the distance between the centers becomes a pitch of 1000 μm so that a gap of at least 500 μm is formed between each chromium (FIG. 1A ( 4)).
After exposure, leave at 25 ° C. for about 30 minutes.
Next, the support layer 6 of the film resist 3 is peeled off by hand to expose the resist layer 5.
These steps are also performed in the yellow room in order to prevent unnecessary exposure of the film resist 3.

Next, as shown in FIG. 1 (4), the film resist 3 is developed.
A 1% sodium carbonate aqueous solution at 30 ° C. is used as the developer, and development is performed at a spray pressure of 0.16 MPa for 80 seconds. After the development, washing with ultrapure water at a spray pressure of 0.12 MPa for 80 seconds is repeated three times.
In the development process, for example, a fully automatic single-wafer developing apparatus manufactured by Tokyo Ohka Kogyo Co., Ltd. can be used.
As a result, the portion masked during development in the resist layer 5 of the film resist 3 is washed away, and a support water passage hole is formed.
These steps are also performed in the yellow room in order to prevent the film resist 3 from being exposed.

Instead of forming the support water passage hole in the resist layer 5 by such photolithography, the support water passage hole is previously drilled in the film resist 3 (resist layer 5) in the stage of preparing the film resist 3. Alternatively, the film resist 3 may be attached to the graphite 1.
As a method for forming a support water passage hole in the film resist 3 in advance, a method using a biopsy trepan can be employed.

  Next, the graphite 1 and the film resist 3 are placed in a clean oven that has been set to 160 ° C. and heated for 1 hour. By this heating step, the polymerization of the resist layer 5 proceeds, and the film resist 3 is cured and chemically stabilized.

Thereafter, the film resist 3 is peeled from the graphite 1 using tweezers as shown in FIG.
At this time, the layer of graphene 2 adhering to the surface of the resist layer 5 is peeled off from the graphite 1 together with the resist layer 5.
Since the graphene 2 layer attached to the resist layer 5 may be laminated more than the desired thickness, if necessary, affix the Scotch tape (registered trademark) (manufactured by 3M) to the surface of the graphene 2 and peel it off. repeat. Since the graphene can be peeled off little by little in the operation of applying and removing the scotch tape, the layer of the graphene 2 can be adjusted to a necessary thickness.
Since the thickness of the graphene 2 layer can be confirmed as a difference in color with an optical microscope, the thickness can be adjusted while confirming.
The layer of graphene 2 obtained in this way is preferably a single layer, but may be several layers.

Thus, the process of peeling the resist layer 5 and the graphene 2 adhering thereto from the graphite 1 is not limited to this point.
For example, the resist layer 5 may be peeled off from the graphite 1 after the film resist 3 is attached to the graphite 1 and before the resist layer 5 is exposed. Further, after the resist layer 5 is exposed, the resist layer 5 may be peeled off from the graphite 1 before being developed. Further, after developing the resist layer 5, it may be peeled off from the graphite 1 before being heated at 160 ° C. for 1 hour.

  Next, as shown in FIG. 1 (6), a graphene water passage for allowing water to pass through the graphene 2 is formed. The graphene water passage hole needs to have a size that allows water to pass through but does not allow impurities or ions to pass through.

The perforation is performed by heating in air at 160 to 250 ° C. for a predetermined time.
In this specification, the term “in the air” is not limited to a mixed gas of about 20% O ₂ and about 80% N ₂ , and other contained gases are not limited as long as they contain 1% or more of O ₂ . Mixed gases including noble gases and other gases are widely accepted.

Conventionally, it has been considered that perforation of graphene 2 does not occur at a low temperature of less than 300 ° C.
However, since the film resist 3 is not damaged at a low temperature of 160 to 250 ° C., and the pores are gradually opened and expanded in the graphene 2, the size of the graphene water passage holes is controlled by the length of the heating time. Can do. Further, when the graphene water passage hole is opened in the air at 200 to 250 ° C., no burning residue is generated, so that the graphene water passage hole can be opened while maintaining a clean surface.
Below 160 ° C., almost no pores can be formed in the graphene 2 even when heated for a long time. In addition, at 250 ° C. or higher, the reaction becomes abrupt and it is difficult to control the pores to a desired size, and the pore sizes are not uniform.
Moreover, it is desirable to set the temperature of low temperature heating to 200-250 degreeC especially.
For example, when a graphene water passage hole is formed in air at 200 ° C. for 20 hours, the filter molded body produced in this way can be made fresh water by removing salt from seawater.

  Further, the predetermined time refers to a time that brings about an effect of forming graphene water passage holes in the graphene 2 in a state where an atmosphere of 160 to 250 ° C. is maintained.

  In addition, although the film resist 3 was used as a support in the above embodiment, the support may be any material that does not affect the low-temperature heat treatment of the graphene 2 and can support the graphene 2 as a filter. For example, a resin or other material having adhesiveness to graphene 2 may be used as a support, or a resin or other support and a heat-resistant adhesive may be used in combination.

The filter molded body thus produced can be used as a filter of a water purifier using a membrane filter as shown in FIG.
For example, the filter molded body is cut into a 1/2 inch circle using a craft punch (made by Curl Office Equipment Co., Ltd.). The filter formed body is attached to the downstream side of the 1/2 inch membrane filter with the resist layer 5 facing upstream and the graphene layer facing downstream, and set in the membrane filter holder 7.
As the membrane filter, for example, “Isopore GTTP” (pore diameter 0.2 μm) manufactured by Merck Co., Ltd., which is a polycarbonate membrane filter, can be used.
As the membrane filter holder 7, for example, “Swinex” manufactured by Merck & Co., Inc. can be used.
In order to filter the solution using such a water purifier, a solution to be filtered (for example, seawater) is put into the syringe 8, connected to the membrane filter holder 7, and the solution is filtered by pushing the syringe 8; Water from which impurities and ions have been removed can be obtained.

  In the first embodiment, the graphene 2 is heated at a low temperature for a predetermined time in air containing oxygen at 160 to 250 ° C. for a predetermined time to form a graphene water passage hole, so that the reaction is gentle and easy to control, and the heating time is reduced. By controlling the length, the holes of a desired size can be uniformly formed in the graphene 2. In addition, since the support can be prevented from being damaged by heating the graphene 2 at a low temperature, the graphene 2 can be prevented from being damaged.

Further, by attaching a film resist 3 made of a negative photoresist as a support to the graphene 2, a filter molded body can be formed without going through a transfer process that causes the graphene 2 to be damaged.
Furthermore, a portion of the film resist 3 where a support water passage hole is to be formed is masked, and a photolithographic technique for exposing the other portion is used, whereby the support water passage hole formed in the film resist 3 is formed. The size and shape can be controlled in detail. Thereby, it becomes possible to form the support body water passage hole in the film resist 3 having a small influence on the ability of the graphene 2 as a filter while increasing the strength as the support body.

<Second embodiment>
Instead of using the film resist 3 made of a negative photoresist in the first embodiment, in the second embodiment, the resist layer 5 is formed by spin-coating a negative liquid resist on the surface of the graphite 1. It is characterized by.
Also in the second embodiment, the same graphite 1 as in the first embodiment is prepared, and the clean surface is exposed with a scotch tape.

In the second embodiment, first, a resist layer 5 is formed on the clean surface of the graphite 1 as shown in FIG.
The resist preferably has the same performance as the first embodiment except that it is a liquid resist.
As such a liquid resist, SU-8 3050 manufactured by Microchem, which is an epoxy resin, was used.
Using a spin coater, a liquid resist is spin-coated on graphite 1 at 3000 rpm for 20 seconds to form a resist layer 5 having a thickness of 50 μm.
After spin coating, soft baking is performed at 95 ° C. for 20 minutes using a hot plate to cure the resist layer 5.
These steps are performed in the yellow room in order to prevent the resist layer 5 from being exposed.

Next, as shown in FIG. 2 (3), the resist layer 5 is exposed and stabilized.
The exposure is performed at 200 mJ / cm ² using an i-line stepper (EXP-2031 manufactured by Oak Manufacturing Co., Ltd.) using a high-pressure mercury lamp.
As in the first embodiment, a part of the surface of the resist layer 5 is masked with chromium to form a support water passage hole (see FIGS. 2A and 2).
After the exposure, soft baking is performed at 65 ° C. for 5 minutes. At this time, the resin is polymerized, and the exposed portion does not dissolve even when developed.
These steps are also performed in the yellow room in order to prevent unnecessary exposure of the resist layer 5.
After exposure, leave at 25 ° C. for about 30 minutes.

Next, as shown in FIG. 2 (4), the resist layer 5 is developed.
For development, a Microchem SU-8 Developer is used.
Put SU-8 Developer into the bat containing the resist layer 5 and rock it for about 8 minutes. Since SU-8 Developer is an organic solvent, the work is performed in a fume hood.
After development, the resist layer 5 is immersed in a new SU-8 Developer and shaken for about 10 seconds, and then immersed in IPA and shaken for 10 seconds. Thereafter, the resist layer 5 and the graphite 1 are taken out and dried.
As a result, the masked portion at the time of development in the resist layer 5 is washed away, and a support water passage hole is formed.
These steps are also performed in the yellow room in order to prevent the resist layer 5 from being exposed.

As shown in FIGS. 2 (5) and 6 (6), from the step of peeling the resist layer 5 and the graphene 2 layer from the graphite 1 to the step of forming the graphene water passage holes in the graphene 2, the same as in the first embodiment. Do.
The prior and subsequent relationship of the step of peeling the resist layer 5 and the graphene 2 layer from the graphite 1 can also be changed as in the first embodiment.

Also in the second embodiment, a liquid resist composed of a negative photoresist as a support is spin-coated on the graphite 1 to form a resist layer 5, thereby forming a filter without passing through a transfer step that causes damage to graphene. The body can be formed.
Furthermore, the size of the support water passage hole formed in the film resist is obtained by applying a mask to the portion where the support water passage hole is to be formed in the resist layer 5 and exposing the other portion. And the shape can be controlled in detail.

<Third embodiment>
In the first embodiment, the graphite 1 is attached to the film resist 3 and the graphene 2 is peeled off, and then the graphene water passage holes are formed in the graphene 2. However, in the third embodiment, before the graphite 1 is attached to the film resist 3 In addition, a graphene water passage hole is formed in the graphite 1.

In the third embodiment, first, graphene water holes are formed in the graphite 1 as shown in FIG.
A clean surface of the basal surface of graphite 1 is spin-coated with a calcium nitrate ethanol solution using a spin coater and then dried at 100 ° C. Thereafter, when heated in an inert gas atmosphere at 300 ° C. for 10 minutes using a muffle furnace, carbon atoms of graphite 1 are oxidized by oxygen atoms in calcium nitrate.
Thereby, a graphene water passage hole can be formed in the graphene 2 in the upper several layers of the basal surface of the graphite 1.

In addition to nitrate, hydrochloride, sulfate, carbonate, or the like may be spin-coated on graphite 1 to form graphene water passage holes.
Of these, nitrates and carbonates that are decomposed and removed by heat treatment are preferable to sulfates and hydrochlorides that remain in graphite 1 and are difficult to remove.
The metal contained in the salt may also be any of alkali metal, alkaline earth metal, lanthanide, and transition metal.
However, since this graphite 1 is used as a water filter, it is preferable to exclude lanthanides and heavy metals with an emphasis on safety. Further, in view of ease of removal when remaining in the graphite 1, a salt using an alkali metal or an alkaline earth metal is preferable to a transition metal.

  In addition to this, as a method of forming graphene water holes in the graphite 1, other physical means such as a method of irradiating the basal surface of the graphite 1 with a focused ion beam (FIB) and a method by plasma treatment are adopted. May be.

Next, as shown in FIGS. 3 (2) and 3 (3), the protective layer 4 of the film resist 3 is peeled off by hand, and the resist layer 5 is placed in close contact with the basal surface on which the graphene water passage holes of the graphite 1 are formed. , Put into a laminator film, and vacuum-press with a vacuum laminator at −50 kPa for 20 seconds.
This step is performed in the yellow room in order to prevent the film resist 3 from being exposed.

Next, the graphite 1 and the film resist 3 are taken out of the laminator film, pressurized at 0.4 MPa while being heated on a hot plate heated to 80 ° C. for 40 seconds, and then naturally cooled to room temperature. In this step, the resist layer 5 adheres to the graphite 1.
Then, it leaves still at 25 degreeC for 15 minutes. Here, by allowing the film resist 3 (resist layer 5) to settle, exposure described later can be performed uniformly.
These steps are also performed in the yellow room in order to prevent the film resist 3 from being exposed.

Next, as shown in FIG. 3 (4), the resist layer 5 is exposed and stabilized.
The exposure is performed at 200 mJ / cm ² using an i-line stepper (EXP-2031 manufactured by Oak Manufacturing Co., Ltd.) using a high-pressure mercury lamp.
As in the first embodiment, a part of the surface of the resist layer 5 is masked with chromium to form a support water passage hole (see FIG. 3 (5)).
After the exposure, soft baking is performed at 65 ° C. for 5 minutes. At this time, the resin is polymerized, and the exposed portion does not dissolve even when developed.
These steps are also performed in the yellow room in order to prevent unnecessary exposure of the film resist 3.
After exposure, leave at 25 ° C. for about 30 minutes.
Thereafter, the support layer 6 of the film resist 3 is peeled off by hand to expose the resist layer 5.

Next, as shown in FIG. 3 (5), the film resist 3 is developed.
A 1% sodium carbonate aqueous solution at 30 ° C. is used as the developer, and development is performed at a spray pressure of 0.16 MPa for 80 seconds. After the development, washing with ultrapure water at a spray pressure of 0.12 MPa for 80 seconds is repeated three times.
In the development process, for example, a fully automatic single-wafer developing apparatus manufactured by Tokyo Ohka Kogyo Co., Ltd. can be used.
As a result, the portion masked during development in the resist layer 5 of the film resist 3 is washed away, and a support water passage hole is formed.
These steps are also performed in the yellow room in order to prevent the film resist 3 from being exposed.

Instead of forming the support water passage hole in the resist layer 5 by such photolithography, the support water passage hole is previously drilled in the film resist 3 (resist layer 5) in the stage of preparing the film resist 3. Alternatively, the film resist 3 may be attached to the graphite 1.
As a method for forming a support water passage hole in the film resist 3 in advance, a method using a biopsy trepan can be employed.

  Next, the graphite 1 and the film resist 3 are placed in a clean oven that has been set to 160 ° C. and heated for 1 hour. By this heating step, the polymerization of the resist layer 5 proceeds, and the film resist 3 is cured and chemically stabilized.

Thereafter, as shown in FIG. 3 (6), the film resist 3 is peeled from the graphite 1 using tweezers.
At this time, the layer of graphene 2 adhering to the surface of the resist layer 5 is peeled off from the graphite 1 together with the resist layer 5.
Since the graphene 2 layer attached to the resist layer 5 may be laminated more than the desired thickness, if necessary, affix the Scotch tape (registered trademark) (manufactured by 3M) to the surface of the graphene 2 and peel it off. repeat. Since the graphene can be peeled off little by little in the operation of applying and removing the scotch tape, the layer of the graphene 2 can be adjusted to a necessary thickness.
Since the thickness of the graphene 2 layer can be confirmed as a difference in color with an optical microscope, the thickness can be adjusted while confirming.
The layer of graphene 2 obtained in this way is preferably a single layer, but may be several layers.

Thus, the process of peeling the resist layer 5 and the graphene 2 adhering thereto from the graphite 1 is not limited to this point.
For example, the resist layer 5 may be peeled off from the graphite 1 after the film resist 3 is attached to the graphite 1 and before the resist layer 5 is exposed. Further, after the resist layer 5 is exposed, the resist layer 5 may be peeled off from the graphite 1 before being developed. Further, after developing the resist layer 5, it may be peeled off from the graphite 1 before being heated at 160 ° C. for 1 hour.

  In the third embodiment, the graphene water passage holes are already formed in the graphene 2 attached to the resist layer 5. However, when it is desired to make the graphene water passage holes larger, after that, in the air at 160 to 250 ° C. It may be heated at a low temperature until it reaches an arbitrary size.

  In the third embodiment, a graphene water hole is formed in the graphene 2 layer on the surface of the graphite 1 and then attached to the film resist 3, and the resist layer 5 is attached in a state where the graphene 2 layer is adhered to the resist layer 5. By peeling from the graphite 1, a filter molded body having graphene water passage holes can be easily formed.

Further, by attaching a film resist 3 made of a negative photoresist as a support to the graphene 2, a filter molded body can be formed without going through a transfer process that causes the graphene 2 to be damaged.
Furthermore, a portion of the film resist 3 where a support water passage hole is to be formed is masked, and a photolithographic technique for exposing the other portion is used, whereby the support water passage hole formed in the film resist 3 is formed. The size and shape can be controlled in detail.

<Test>
Tests were conducted to determine the effect of the present invention.
Single-layer carbon nanohorn (SWNH) is used for the measurement test. SWNH has the same basic structure as graphene, but has a conical shape.
In this test, the adsorption amount of nitrogen at 77 K was measured using an adsorption measuring device, Autosorb-iQ, manufactured by Cantachrome Instruments Japan GK. Nitrogen gas is supplied to the outside of SWNH, and the amount of nitrogen gas is measured after a predetermined time. When there is a hole through which nitrogen can pass on the peripheral surface of SWNH, nitrogen enters the inside of SWNH and is adsorbed on the inner wall. Therefore, the difference between the amount of supplied nitrogen and the amount of nitrogen outside SWNH after the test causes The amount of adsorption can be understood, and the size and size of the holes can be grasped.

In FIG. 4 (a), untreated SWNH, SWNH treated in air at 250 ° C. for 20 hours, and SWNH treated in air at 250 ° C. for 70 hours are prepared. Nitrogen was supplied at different temperatures and the nitrogen adsorption amount was measured.
It can be seen that the SWNH treated for 20 hours has a large increase in the amount of nitrogen adsorbed from the low pressure to the high pressure compared to the SWNH that has not been treated, and thus a hole through which nitrogen passes is formed.
Further, SWNH treated for 70 hours has an increased amount of adsorption compared with SWNH treated for 20 hours, which means that the number of SWNHs with holes is increased. That is, the amount of adsorption is increased by increasing the number of formed holes and consequently increasing the ratio of SWNH having holes. Therefore, it can be seen that the number of holes has increased.

In FIG. 4 (b), untreated SWNH and SWNH are treated in air at 200 ° C. for 20 hours, SWNH is treated in air at 200 ° C. for 70 hours, and SWNH is treated in air at 200 ° C. A sample treated for 100 hours and a sample treated with SWNH in air at 200 ° C. for 150 hours were prepared. Nitrogen was supplied at different relative pressures, and the nitrogen adsorption amount was measured.
When SNWH is treated at 200 ° C., the carbon adsorption amount increases as the treatment time is increased, although not as much as when treated at 250 ° C. That is, it can be seen that the number of holes increased as the treatment time was increased.

In FIG. 5, untreated SWNH, SWNH treated in air at 180 ° C. for 20 hours, and SWNH treated in air at 180 ° C. for 70 hours are prepared. Nitrogen was supplied and the nitrogen adsorption amount was measured.
It can be seen that the SNWH treated for 50 hours has an increased amount of nitrogen adsorbed from the low pressure to the high pressure compared to the untreated SNWH, and a hole through which nitrogen passes is formed.
On the other hand, the amount of nitrogen adsorbed in SNWH processed for 70 hours is not substantially increased compared to SNWH processed for 50 hours. Therefore, it was found that the number of holes hardly increased at 180 ° C. even if the treatment time was increased.

Next, ion selectivity is measured for the graphene in which the holes are formed.
Since the hydrated ionic radius of the cation is Li ⁺ > Na ⁺ > K ⁺ > Rb ⁺ > Cs ⁺ , the ion selectivity of the filter using graphene is measured according to the permeability of each ion.
In the test, 24 mg of SWNH was added to 6 mL of a 20 μmol / L Li, Na, K, Rb, Cs mixed solution and allowed to stand at 30 ° C. for 24 hours, and then the ion concentration of the solution was measured by an ion chromatograph. If cations are attached to the inside of the SWNH through the holes opened in the SWNH, the measured ion concentration becomes small. 6 (a) and 6 (b) are graphs in which the amount of ions that have permeated through the pores is measured from the concentration change.

In Fig. 6 (a), SWNH treated in air at 250 ° C for 20 hours, SWNH treated in air at 250 ° C for 70 hours, and SWNH treated in air at 250 ° C for 100 hours are prepared. And put into the mixed solution.
As a result, it can be seen that all cations are permeated regardless of the treatment time. Therefore, it was found that when the treatment was performed at 250 ° C. for 20 hours or more, the pores formed in the SWNH were enlarged and there was no ion selectivity.

In FIG. 6 (b), SWNH treated in air at 200 ° C. for 20 hours, SWNH treated in air at 200 ° C. for 50 hours, SWNH treated in air at 200 ° C. for 70 hours, SWNH Prepared in a 200 ° C. air for 100 hours and SWNH treated in a 200 ° C. air for 150 hours were prepared and placed in a mixed solution.
As a result, SWNH treated for 20 hours hardly transmits ions with a large hydrated ion radius such as Li and Na, but transmits ions with a small hydrated ion radius such as K, Rb, and Cs. I understood.
On the other hand, in SWNH processed for 50 hours or more, it turned out that a hole becomes large and all the ions permeate | transmit.

FIG. 7 shows a comparison of ion selectivity for each heating temperature, with a treatment time of 20 hours.
SWNH treated in air at 140 ° C. for 20 hours, SWNH treated in air at 160 ° C. for 20 hours, SWNH treated in air at 180 ° C. for 20 hours, SWNH treated in air at 200 ° C. What processed for 20 hours and what processed SWNH for 20 hours in the air of 250 degreeC were prepared, and it put into the mixed solution.
In SWNH processed at 140 degreeC, it turns out that a hole is hardly opened and ion has hardly permeate | transmitted.
It can be seen that SWNH treated at 160 ° C. and SWNH treated at 180 ° C. have small pores and allow only a small amount of ions to pass through. It can also be seen that the permeation amounts of K, Rb, and Cs are small and do not have ion selectivity.
It can be seen that SWNH treated at 200 ° C. has ion selectivity because it has a small amount of permeation of Li and Na and a large amount of permeation of K, Rb and Cs.
It can be seen that SWNH treated at 250 ° C. has a large permeation amount of all ions.

Moreover, in FIG. 8, FIG. 9, the filter molded object which has the graphene 2 manufactured by 1st embodiment as mentioned above is set to the membrane filter holder 7, and 20 micromol / L Li, Na, K, Rb from the syringe 8 is set. , Cs mixed solution was permeated and the ion concentration of the permeate was measured.
The graphene prepared what was processed at 160 degreeC for 20 hours, what was processed at 200 degreeC for 20 hours, and what was processed at 250 degreeC for 20 hours was prepared.

As a result, as shown in FIG. 9, the graphene treated at 160 ° C. has small pores and hardly transmits each ion.
It was found that the graphene treated at 200 ° C. hardly transmitted Li and Na but allowed K, Rb, and Cs to pass.
Graphene treated at 250 ° C. was found to have large pores and allow all ions to pass through.

DESCRIPTION OF SYMBOLS 1 Graphite 2 Graphene 3 Film resist 4 Protective layer 5 Resist layer 6 Support layer 7 Membrane filter holder 8 Syringe

Claims (4)

A method for producing a filter molded body having a graphene layer as a filter material,
Forming a support layer on the surface of the graphite;
Forming a support water passage hole in the support layer;
Peeling the support layer from the graphite in a state where the graphene layer on the surface of the graphite is attached to the support layer;
And a step of heating the graphene layer in air containing oxygen at 160 to 250 ° C. for a predetermined time to form a graphene water passage hole. The support is a negative photoresist,
2. The step of forming the support water passage hole in the layer of the support includes the step of exposing a portion of the photoresist other than the portion where the support water passage hole is to be formed. The manufacturing method of the filter molded object of description.   The method for producing a filter molded body according to claim 1, wherein the step of forming the graphene water passage hole by holding the graphene layer at a low temperature is performed in air containing oxygen at 200 to 250 ° C. . A method for producing a filter molded body having a graphene layer as a filter material,
Forming graphene water passage holes in the graphene layer on the surface of the graphite;
Forming a support layer on the surface of the graphite where the graphene layer is present;
Forming a support water passage hole in the support layer;
And a step of peeling the support layer from the graphite in a state where the graphene layer is adhered to the support layer.

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